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        <ol class="chapter"><li><a href="../index.html"><strong aria-hidden="true">1.</strong> 超过 88 道练习，任点</a></li><li><a href="../low.html"><strong aria-hidden="true">2.</strong> 易</a></li><li><ol class="section"><li><a href="../hello-world/README.zh.html"><strong aria-hidden="true">2.1.</strong> hello world</a></li><li><a href="../gigasecond/README.zh.html"><strong aria-hidden="true">2.2.</strong> 千兆秒 &gt;&lt; Gigasecond)</a></li><li><a href="../leap/README.zh.html"><strong aria-hidden="true">2.3.</strong> 闰年 &gt;&lt; Leap</a></li><li><a href="../raindrops/README.zh.html"><strong aria-hidden="true">2.4.</strong> 雨滴声 &gt;&lt; Raindrops</a></li><li><a href="../reverse-string/README.zh.html"><strong aria-hidden="true">2.5.</strong> 反转字符串 &gt;&lt; Reverse String</a></li><li><a href="../nth-prime/README.zh.html"><strong aria-hidden="true">2.6.</strong> 第 n 个素数 &gt;&lt; Nth Prime</a></li><li><a href="../bob/README.zh.html"><strong aria-hidden="true">2.7.</strong> 迟钝孩子 &gt;&lt; Bob</a></li><li><a href="../beer-song/README.zh.html"><strong aria-hidden="true">2.8.</strong> 啤酒之歌 &gt;&lt; Beer Song</a></li><li><a href="../proverb/README.zh.html"><strong aria-hidden="true">2.9.</strong> 谚语串烧 &gt;&lt; Proverb</a></li><li><a href="../difference-of-squares/README.zh.html"><strong aria-hidden="true">2.10.</strong> 平方差 &gt;&lt; Difference Of Squares</a></li><li><a href="../sum-of-multiples/README.zh.html"><strong aria-hidden="true">2.11.</strong> 倍数之和 &gt;&lt; Sum Of Multiples</a></li><li><a href="../grains/README.zh.html"><strong aria-hidden="true">2.12.</strong> 谷物 &gt;&lt; Grains</a></li><li><a href="../pythagorean-triplet/README.zh.html"><strong aria-hidden="true">2.13.</strong> 勾股数 &gt;&lt; Pythagorean Triplet</a></li><li><a href="../prime-factors/README.zh.html"><strong aria-hidden="true">2.14.</strong> 素数因子 &gt;&lt; Prime Factors</a></li><li><a href="../series/README.zh.html"><strong aria-hidden="true">2.15.</strong> 子串 &gt;&lt; Series</a></li><li><a href="../armstrong-numbers/README.zh.html"><strong aria-hidden="true">2.16.</strong> 水仙花数 &gt;&lt; Armstrong Numbers</a></li><li><a href="../collatz-conjecture/README.zh.html"><strong aria-hidden="true">2.17.</strong> 3n+1 猜想 &gt;&lt; Collatz Conjecture</a></li><li><a href="../diffie-hellman/README.zh.html"><strong aria-hidden="true">2.18.</strong> 迪菲-赫尔曼密钥交换 &gt;&lt; Diffie Hellman</a></li></ol></li><li><a href="../medium.html"><strong aria-hidden="true">3.</strong> 中等</a></li><li><ol class="section"><li><a href="../saddle-points/README.zh.html"><strong aria-hidden="true">3.1.</strong> 鞍点 &gt;&lt; Saddle Points</a></li><li><a href="../isogram/README.zh.html"><strong aria-hidden="true">3.2.</strong> 等值线 &gt;&lt; Isogram</a></li><li><a href="../say/README.zh.html"><strong aria-hidden="true">3.3.</strong> 英文说数字 &gt;&lt; Say</a></li><li><a href="../run-length-encoding/README.zh.html"><strong aria-hidden="true">3.4.</strong> 游程编码 &gt;&lt; Run Length Encoding</a></li><li><a href="../isbn-verifier/README.zh.html"><strong aria-hidden="true">3.5.</strong> 图书编号 &gt;&lt; ISBN Verifier</a></li><li><a href="../perfect-numbers/README.zh.html"><strong aria-hidden="true">3.6.</strong> 数字也能分类 &gt;&lt; Perfect Numbers</a></li><li><a href="../clock/README.zh.html"><strong aria-hidden="true">3.7.</strong> 时钟 &gt;&lt; Clock</a></li><li><a href="../dot-dsl/README.zh.html"><strong aria-hidden="true">3.8.</strong> DOT DSL</a></li><li><a href="../hamming/README.zh.html"><strong aria-hidden="true">3.9.</strong> 汉明距离 &gt;&lt; Hamming</a></li><li><a href="../simple-linked-list/README.zh.html"><strong aria-hidden="true">3.10.</strong> 简单链表 &gt;&lt; Simple Linked List</a></li><li><a href="../pascals-triangle/README.zh.html"><strong aria-hidden="true">3.11.</strong> 杨辉三角形 &gt;&lt; Pascal's Triangle</a></li><li><a href="../scrabble-score/README.zh.html"><strong aria-hidden="true">3.12.</strong> 字母的分数游戏 &gt;&lt; Scrabble Score</a></li><li><a href="../pangram/README.zh.html"><strong aria-hidden="true">3.13.</strong> 全字母句 &gt;&lt; Pangram</a></li><li><a href="../paasio/README.zh.html" class="active"><strong aria-hidden="true">3.14.</strong> PaaS-IO-报告 &gt;&lt; Paasio</a></li><li><a href="../nucleotide-count/README.zh.html"><strong aria-hidden="true">3.15.</strong> 核苷酸计数 &gt;&lt; Nucleotide Count</a></li><li><a href="../luhn/README.zh.html"><strong aria-hidden="true">3.16.</strong> 模 10 算法 &gt;&lt; Luhn</a></li><li><a href="../largest-series-product/README.zh.html"><strong aria-hidden="true">3.17.</strong> 最大数字子串乘积 &gt;&lt; Largest Series Product</a></li><li><a href="../word-count/README.zh.html"><strong aria-hidden="true">3.18.</strong> 单词计数 &gt;&lt; Word Count</a></li><li><a href="../atbash-cipher/README.zh.html"><strong aria-hidden="true">3.19.</strong> Atbash 加密 &gt;&lt; Atbash Cipher</a></li><li><a href="../crypto-square/README.zh.html"><strong aria-hidden="true">3.20.</strong> 密码矩形 &gt;&lt; Crypto Square</a></li><li><a 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aria-hidden="true">3.29.</strong> 三角形</a></li><li><a href="../roman-numerals/README.zh.html"><strong aria-hidden="true">3.30.</strong> 罗马数字 &gt;&lt; Roman Numerals</a></li><li><a href="../all-your-base/README.zh.html"><strong aria-hidden="true">3.31.</strong> 你所的基本</a></li><li><a href="../grade-school/README.zh.html"><strong aria-hidden="true">3.32.</strong> 学册</a></li><li><a href="../binary-search/README.zh.html"><strong aria-hidden="true">3.33.</strong> 二分查找</a></li><li><a href="../robot-simulator/README.zh.html"><strong aria-hidden="true">3.34.</strong> 机器人模拟器</a></li><li><a href="../bracket-push/README.zh.html"><strong aria-hidden="true">3.35.</strong> 括号配套</a></li><li><a href="../luhn-from/README.zh.html"><strong aria-hidden="true">3.36.</strong> Luhn From</a></li><li><a href="../queen-attack/README.zh.html"><strong aria-hidden="true">3.37.</strong> 皇后 攻击</a></li><li><a href="../bowling/README.zh.html"><strong aria-hidden="true">3.38.</strong> 保龄球</a></li><li><a href="../sublist/README.zh.html"><strong aria-hidden="true">3.39.</strong> 子列表</a></li><li><a href="../space-age/README.zh.html"><strong aria-hidden="true">3.40.</strong> 地球年</a></li><li><a href="../luhn-trait/README.zh.html"><strong aria-hidden="true">3.41.</strong> Luhn Trait</a></li><li><a href="../macros/README.zh.html"><strong aria-hidden="true">3.42.</strong> 宏</a></li><li><a href="../allergies/README.zh.html"><strong aria-hidden="true">3.43.</strong> 过敏</a></li><li><a href="../variable-length-quantity/README.zh.html"><strong aria-hidden="true">3.44.</strong> 可变长度数量</a></li><li><a href="../phone-number/README.zh.html"><strong aria-hidden="true">3.45.</strong> 电话号码</a></li><li><a href="../wordy/README.zh.html"><strong aria-hidden="true">3.46.</strong> 罗唆</a></li><li><a href="../tournament/README.zh.html"><strong aria-hidden="true">3.47.</strong> 比赛</a></li><li><a href="../custom-set/README.zh.html"><strong aria-hidden="true">3.48.</strong> 自定义 set</a></li><li><a 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                <main>
                    <a class="header" href="#paasio" id="paasio"><h1>Paasio</h1></a>
<a class="header" href="#1-readme" id="1-readme"><h2>1. Readme</h2></a>
<a class="header" href="#paasio-1" id="paasio-1"><h1>Paasio</h1></a>
<p>报告网络 IO 统计.</p>
<p>你正在写一个<a href="http://en.wikipedia.org/wiki/Platform_as_a_service">PaaS</a>，你需要一种给网络和文件系统使用的帐单.</p>
<p>为报告 IO 统计信息的网络连接和文件，创建包装器。包装器必须报告:</p>
<ul>
<li>读取/写入的字节总数.</li>
<li>读取/写入操作的总数.</li>
</ul>
<a class="header" href="#网络和文件的抽象" id="网络和文件的抽象"><h2>网络和文件的抽象</h2></a>
<p>网络和文件操作，是实现了<a href="https://doc.rust-lang.org/std/io/trait.Read.html"><code>io::Read</code></a>和<a href="https://doc.rust-lang.org/std/io/trait.Write.html"><code>io::Write</code></a> <code>traits</code> 的。因此,有必要为您的类型实现这些特性.</p>
<a class="header" href="#资源" id="资源"><h2>资源</h2></a>
<p>布瑞恩松岛<a href="https://github.com/bmatsuo">https://github.com/bmatsuo</a></p>
<a class="header" href="#2-开始你的表演" id="2-开始你的表演"><h2>2. 开始你的表演</h2></a>
<pre><pre class="playpen"><code class="language-rust editable">use std::io::{Read, Result, Write};

pub struct ReadStats&lt;R&gt;(::std::marker::PhantomData&lt;R&gt;);

impl&lt;R: Read&gt; ReadStats&lt;R&gt; {
   // _wrapped is ignored because R is not bounded on Debug or Display and therefore
   // can't be passed through format!(). For actual implementation you will likely
   // wish to remove the leading underscore so the variable is not ignored.
   pub fn new(_wrapped: R) -&gt; ReadStats&lt;R&gt; {
       unimplemented!()
   }

   pub fn get_ref(&amp;self) -&gt; &amp;R {
       unimplemented!()
   }

   pub fn bytes_through(&amp;self) -&gt; usize {
       unimplemented!()
   }

   pub fn reads(&amp;self) -&gt; usize {
       unimplemented!()
   }
}

impl&lt;R: Read&gt; Read for ReadStats&lt;R&gt; {
   fn read(&amp;mut self, buf: &amp;mut [u8]) -&gt; Result&lt;usize&gt; {
       unimplemented!(&quot;Collect statistics about this call reading {:?}&quot;, buf)
   }
}

pub struct WriteStats&lt;W&gt;(::std::marker::PhantomData&lt;W&gt;);

impl&lt;W: Write&gt; WriteStats&lt;W&gt; {
   // _wrapped is ignored because W is not bounded on Debug or Display and therefore
   // can't be passed through format!(). For actual implementation you will likely
   // wish to remove the leading underscore so the variable is not ignored.
   pub fn new(_wrapped: W) -&gt; WriteStats&lt;W&gt; {
       unimplemented!()
   }

   pub fn get_ref(&amp;self) -&gt; &amp;W {
       unimplemented!()
   }

   pub fn bytes_through(&amp;self) -&gt; usize {
       unimplemented!()
   }

   pub fn writes(&amp;self) -&gt; usize {
       unimplemented!()
   }
}

impl&lt;W: Write&gt; Write for WriteStats&lt;W&gt; {
   fn write(&amp;mut self, buf: &amp;[u8]) -&gt; Result&lt;usize&gt; {
       unimplemented!(&quot;Collect statistics about this call writing {:?}&quot;, buf)
   }

   fn flush(&amp;mut self) -&gt; Result&lt;()&gt; {
       unimplemented!()
   }
}

</code></pre></pre>
<a class="header" href="#3-测试代码查看" id="3-测试代码查看"><h2>3. 测试代码查看</h2></a>
<pre><pre class="playpen"><code class="language-rust">
# #![allow(unused_variables)]
#fn main() {
/// test a few read scenarios
macro_rules! test_read {
   ($(#[$attr:meta])* $modname:ident ($input:expr, $len:expr)) =&gt; {
       mod $modname {
           use std::io::{Read, BufReader};


           const CHUNK_SIZE: usize = 2;

           $(#[$attr])*
           #[test]
           fn test_read_passthrough() {
               let data = $input;
               let size = $len(&amp;data);
               let mut reader = ReadStats::new(data);

               let mut buffer = Vec::with_capacity(size);
               let qty_read = reader.read_to_end(&amp;mut buffer);

               assert!(qty_read.is_ok());
               assert_eq!(size, qty_read.unwrap());
               assert_eq!(size, buffer.len());
               // 2: first to read all the data, second to check that
               // there wasn't any more pending data which simply didn't
               // fit into the existing buffer
               assert_eq!(2, reader.reads());
               assert_eq!(size, reader.bytes_through());
           }

           $(#[$attr])*
           #[test]
           fn test_read_chunks() {
               let data = $input;
               let size = $len(&amp;data);
               let mut reader = ReadStats::new(data);

               let mut buffer = [0_u8; CHUNK_SIZE];
               let mut chunks_read = 0;
               while reader.read(&amp;mut buffer[..]).unwrap_or_else(|_| panic!(&quot;read failed at chunk {}&quot;, chunks_read+1)) &gt; 0 {
                   chunks_read += 1;
               }

               assert_eq!(size / CHUNK_SIZE, chunks_read);
               // we read once more than the number of chunks, because the final
               // read returns 0 new bytes
               assert_eq!(1+chunks_read, reader.reads());
               assert_eq!(size, reader.bytes_through());
           }

           $(#[$attr])*
           #[test]
           fn test_read_buffered_chunks() {
               let data = $input;
               let size = $len(&amp;data);
               let mut reader = BufReader::new(ReadStats::new(data));

               let mut buffer = [0_u8; CHUNK_SIZE];
               let mut chunks_read = 0;
               while reader.read(&amp;mut buffer[..]).unwrap_or_else(|_| panic!(&quot;read failed at chunk {}&quot;, chunks_read+1)) &gt; 0 {
                   chunks_read += 1;
               }

               assert_eq!(size / CHUNK_SIZE, chunks_read);
               // the BufReader should smooth out the reads, collecting into
               // a buffer and performing only two read operations:
               // the first collects everything into the buffer,
               // and the second ensures that no data remains
               assert_eq!(2, reader.get_ref().reads());
               assert_eq!(size, reader.get_ref().bytes_through());
           }
       }
   };
}

/// test a few write scenarios
macro_rules! test_write {
   ($(#[$attr:meta])* $modname:ident ($input:expr, $len:expr)) =&gt; {
       mod $modname {
           use std::io::{self, Write, BufWriter};


           const CHUNK_SIZE: usize = 2;
           $(#[$attr])*
           #[test]
           fn test_write_passthrough() {
               let data = $input;
               let size = $len(&amp;data);
               let mut writer = WriteStats::new(Vec::with_capacity(size));
               let written = writer.write(data);
               assert!(written.is_ok());
               assert_eq!(size, written.unwrap());
               assert_eq!(size, writer.bytes_through());
               assert_eq!(1, writer.writes());
               assert_eq!(data, writer.get_ref().as_slice());
           }

           $(#[$attr])*
           #[test]
           fn test_sink_oneshot() {
               let data = $input;
               let size = $len(&amp;data);
               let mut writer = WriteStats::new(io::sink());
               let written = writer.write(data);
               assert!(written.is_ok());
               assert_eq!(size, written.unwrap());
               assert_eq!(size, writer.bytes_through());
               assert_eq!(1, writer.writes());
           }

           $(#[$attr])*
           #[test]
           fn test_sink_windowed() {
               let data = $input;
               let size = $len(&amp;data);
               let mut writer = WriteStats::new(io::sink());

               let mut chunk_count = 0;
               for chunk in data.chunks(CHUNK_SIZE) {
                   chunk_count += 1;
                   let written = writer.write(chunk);
                   assert!(written.is_ok());
                   assert_eq!(CHUNK_SIZE, written.unwrap());
               }
               assert_eq!(size, writer.bytes_through());
               assert_eq!(chunk_count, writer.writes());
           }

           $(#[$attr])*
           #[test]
           fn test_sink_buffered_windowed() {
               let data = $input;
               let size = $len(&amp;data);
               let mut writer = BufWriter::new(WriteStats::new(io::sink()));

               for chunk in data.chunks(CHUNK_SIZE) {
                   let written = writer.write(chunk);
                   assert!(written.is_ok());
                   assert_eq!(CHUNK_SIZE, written.unwrap());
               }
               // at this point, nothing should have yet been passed through to
               // our writer
               assert_eq!(0, writer.get_ref().bytes_through());
               assert_eq!(0, writer.get_ref().writes());

               // after flushing, everything should pass through in one go
               assert!(writer.flush().is_ok());
               assert_eq!(size, writer.get_ref().bytes_through());
               assert_eq!(1, writer.get_ref().writes());
           }
       }
   };
}

#[test]
fn test_create_stats() {
   let mut data: Vec&lt;u8&gt; = Vec::new();
   let _ = ReadStats::new(data.as_slice());
   let _ = WriteStats::new(data.as_mut_slice());
}

test_read!( read_string (
   &quot;Twas brillig, and the slithy toves/Did gyre and gimble in the wabe:/All mimsy were the borogoves,/And the mome raths outgrabe.&quot;.as_bytes(),
   |d: &amp;[u8]| d.len()
));
test_write!( write_string (
   &quot;Beware the Jabberwock, my son!/The jaws that bite, the claws that catch!/Beware the Jubjub bird, and shun/The frumious Bandersnatch!&quot;.as_bytes(),
   |d: &amp;[u8]| d.len()
));

test_read!(read_byte_literal(
   &amp;[1_u8, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144][..],
   |d: &amp;[u8]| d.len()
));
test_write!(write_byte_literal(
   &amp;[2_u8, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,][..],
   |d: &amp;[u8]| d.len()
));

test_read!(read_file(
   ::std::fs::File::open(&quot;README.md&quot;).expect(&quot;readme must be present&quot;),
   |f: &amp;::std::fs::File| f.metadata().expect(&quot;metadata must be present&quot;).len() as usize
));

#[test]
fn read_stats_by_ref_returns_wrapped_reader() {
   use ReadStats;

   let input =
       &quot;Why, sometimes I've believed as many as six impossible things before breakfast&quot;.as_bytes();
   let reader = ReadStats::new(input);
   assert_eq!(reader.get_ref(), &amp;input);
}

#}</code></pre></pre>
<a class="header" href="#4-答案" id="4-答案"><h2>4. 答案</h2></a>
<p><details></p>
<pre><pre class="playpen"><code class="language-rust">
# #![allow(unused_variables)]
#fn main() {
use std::io::{Read, Result, Write};

pub struct WriteStats&lt;W: Write&gt; {
   inner: W,
   bytes: usize,
   writes: usize,
}

impl&lt;W: Write&gt; WriteStats&lt;W&gt; {
   pub fn new(wrapped: W) -&gt; WriteStats&lt;W&gt; {
       WriteStats {
           inner: wrapped,
           bytes: 0,
           writes: 0,
       }
   }

   pub fn get_ref(&amp;self) -&gt; &amp;W {
       &amp;self.inner
   }

   pub fn bytes_through(&amp;self) -&gt; usize {
       self.bytes
   }

   pub fn writes(&amp;self) -&gt; usize {
       self.writes
   }
}

impl&lt;W: Write&gt; Write for WriteStats&lt;W&gt; {
   fn write(&amp;mut self, buf: &amp;[u8]) -&gt; Result&lt;usize&gt; {
       self.writes += 1;
       let written = self.inner.write(buf)?;
       self.bytes += written;
       Ok(written)
   }

   fn flush(&amp;mut self) -&gt; Result&lt;()&gt; {
       self.inner.flush()
   }
}

pub struct ReadStats&lt;R: Read&gt; {
   inner: R,
   bytes: usize,
   reads: usize,
}

impl&lt;R: Read&gt; ReadStats&lt;R&gt; {
   pub fn new(wrapped: R) -&gt; ReadStats&lt;R&gt; {
       ReadStats {
           inner: wrapped,
           bytes: 0,
           reads: 0,
       }
   }

   pub fn get_ref(&amp;self) -&gt; &amp;R {
       &amp;self.inner
   }

   pub fn bytes_through(&amp;self) -&gt; usize {
       self.bytes
   }

   pub fn reads(&amp;self) -&gt; usize {
       self.reads
   }
}

impl&lt;R: Read&gt; Read for ReadStats&lt;R&gt; {
   fn read(&amp;mut self, buf: &amp;mut [u8]) -&gt; Result&lt;usize&gt; {
       self.reads += 1;
       let read = self.inner.read(buf)?;
       self.bytes += read;
       Ok(read)
   }
}

#}</code></pre></pre>
<p></details></p>
<hr />
<hr />
<a class="header" href="#填充相关" id="填充相关"><h2>填充/相关</h2></a>

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